Hi Schel,
I think you need to go in to the school and speak to the teachers, tell them that you were happy with your sons progress and his attitude to school before Christmas and that in your opinion the new class situation is not good for your son.
That said, the school may not be able to do anything about the change in the combined class and you will need to work with the teachers in addressing your sons behaviour, home/school partnerships work well in the UK so that discipline and rewards are consistent for the child at home and at school. As your son is only 6 years old he is well placed to change his behaviour but only with the right support from you and his teachers. Good luck

hi there! i think your son is botherd about something i think you should talk to him patiently. or his having a hard time cooping up with the double classroom thing. just like you said his not normally that way,